The role of larval substrate specialization and female oviposition in mediating species diversity of closely-related sepsid flies (Diptera: Sepsidae)

Laux, Amelie; Wegmann, Alexandra; Roy, Jeannine; Gourgoulianni, Natalia; Blanckenhorn, Wolf U.; Rohner, Patrick T.

doi:10.14411/eje.2019.008

Cited by 4 publications

(2 citation statements)

References 51 publications

(29 reference statements)

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“…Although all species investigated here (except T. minor) commonly co-occur on livestock excrements (at least in Central Europe), the mechanisms that allow more than 10 closely related species of the genus Sepsis to co-exist in the same habitat remain contentious even after this study. Previous studies suggested little larval substrate specialization (Laux et al 2019) and only minor geographic, altitudinal or seasonal (including diurnal) variation in occurrence (Rohner et al 2014(Rohner et al , 2015(Rohner et al , 2019. Therefore these species have largely overlapping ecological niches.…”

Section: Discussionmentioning

confidence: 95%

Sexual size dimorphism is associated with reproductive life history trait differentiation in coexisting sepsid flies

Blanckenhorn

Baur

Busso

et al. 2020

Oikos

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Organismal life histories evolve as syndromes, resulting in correlated evolutionary differentiation of key traits that ultimately aid in discerning species. Reproductive success depends both on the absolute body size of an individual and its size relative to the opposite sex: sexual size dimorphism. In an attempt to further elucidate their coexistence and ecological diversification, we compared standard life history (first reproduction, clutch size, egg size) and associated reproductive trait differentiation of 15 widespread European sepsid fly species (Diptera: Sepsidae) under laboratory common garden conditions. Despite relatively uniform body sizes, sexual dimorphism ranged from female-to male-biased, and development time varied twofold across species. We expected, and found, the abundant and relatively large species (Sepsis cynipsea, punctum, thoracica) with often male-biased SSD to lay larger but fewer eggs and show fast-developing, fast-reproducing life histories with aggressive (coercive) mating behavior characterized by short mating latencies and male conflict. In contrast, the smaller and more dispersed species with female-biased SSD (S. flavimana, orthocnemis, violacea) laid smaller but more eggs, showing a generally slower life history with long and delayed copulation and oviposition, high mating reluctance fostering extensive inter-sexual conflict, and more elaborate male (pre-)copulatory courtship. Two Saltella species were exceptional, being large, developing slowly, nevertheless copulating soon after adult emergence, profusely and briefly. The documented life history differentiation seems partly driven by sexual selection leading to male-biased dimorphism, rather than undetermined ecological selection, but regardless appears insufficient to explain the coexistence and diversification of these sepsid species in European pastoral landscapes.

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Section: Discussionmentioning

confidence: 95%

Sexual size dimorphism is associated with reproductive life history trait differentiation in coexisting sepsid flies

Blanckenhorn

Baur

Busso

et al. 2020

Oikos

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“…Thus, there is still the possibility that any research misses the crucial factors or investigates the 'wrong' traits. The here discussed species all lay their eggs into cow (and other) dung(Laux et al 2019), which the larvae consume and thus recycle to ultimately pupate in the ground underneath. Since dung can be limited not only in absolute abundance but also in space and time, intra-and inter-speci c competition might very well be much stronger at the juvenile rather than the adult stage (Ezeakacha and Yee 2019, Gurney and Nisbet 1985,Khelifa et al 2019, Moll andBrown 2008,…”

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confidence: 99%

Lacking sex-specific temperature preferences of 9 coexisting temperate sepsid dung fly species (Diptera: Sepsidae)

Dallo,

Kapun,

Blanckenhorn

2024

Preprint

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Many similar sepsid dung fly species coexist on European pastures, contradicting conventional wisdom of niche theory and competitive exclusion. We hypothesized that closely-related sepsid species on the same pasture in Switzerland avoid each other by having different spatio-temporal microhabitat niche preferences, thus enabling coexistence. A thermal racetrack experiment in the laboratory tested the thermal preferences of males and females of 9 coexisting temperate Sepsis dung fly species from Switzerland at two acclimation temperatures. The sepsid species investigated here showed no strong differences in thermal preferences. Flies of all species preferred to settle at cooler temperatures, and otherwise utilized the entire range (from 12°C to 30°C) offered for their activities. This was the case for both sexes, and also for both acclimation temperatures (18°C, 24°C). Our findings suggest that physiological thermal adaptation or acclimation is not an important mechanism by which adult sepsid flies avoid interspecific competition. Our experiment supports previous findings of widespread sepsid flies lacking local adaptation but high phenotypic plasticity, again highlighting the necessity of experimentally assessing putative biological mechanisms facilitating coexistence.

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Are yellow dung flies domesticated cow dung specialists?

Blanckenhorn,

Burkhard

2023

AlpEnt

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The theory of niche differentiation implies some extent of specialization of species with regard to key resources, notably food. Coprophagous (dung-eating) insect larvae play a critical role in the decomposition of livestock dung in modern and traditional agricultural grasslands. The yellow dung fly (Scathophaga stercoraria L.; Diptera: Scathophagidae) is one of the largest, most common and abundant dung decomposers on pastures in cold-temperate regions across the entire northern hemisphere. As this fly is often associated with domesticated cattle or dairy cows, which are commonly kept for human nutrition worldwide (beef, milk, cheese, etc.), it is sometimes suspected to be a cow dung specialist. However, yellow dung flies are regularly active on and around other dung types, and must have reproduced on dung of wild vertebrates before the domestication of cattle. We therefore experimentally studied the performance of yellow dung fly larvae on dung of various large domestic vs. wild mammals (cow, horse, wild boar, red deer) in the laboratory in Switzerland. Larval performance in terms of juvenile survival, egg-to-adult development time, growth rate, and final adult body size, the major life history indicators of individual reproductive success, did not vary greatly among the various dung types tested. Thus, yellow dung flies can successfully reproduce on multiple types of mammal (vertebrate) dung, wild and domestic, and are therefore dung generalists rather than specialists. We conclude that yellow dung flies are common in European low- and highlands because they could plastically shift to dung of common herbivorous livestock after their domestication without losing the ability to reproduce on dung of common wild mammals.

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The role of larval substrate specialization and female oviposition in mediating species diversity of closely-related sepsid flies (Diptera: Sepsidae)

Cited by 4 publications

References 51 publications

Sexual size dimorphism is associated with reproductive life history trait differentiation in coexisting sepsid flies

Sexual size dimorphism is associated with reproductive life history trait differentiation in coexisting sepsid flies

Lacking sex-specific temperature preferences of 9 coexisting temperate sepsid dung fly species (Diptera: Sepsidae)

Are yellow dung flies domesticated cow dung specialists?

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